Autonomous vehicles are vehicles having computer control systems that attempt to perform the driving tasks that are conventionally performed by a human driver. Stated generally, the purpose of a control system of an autonomous vehicle is to guide the vehicle from a current location to a destination. In reality, multiple constraints are placed on the control system. For example, the route chosen by the control system might be constrained to travel along a public roadway, to avoid obstacles, and to travel in conformance with traffic laws. Travel upon public roadways along a determined route from a current location to a destination provides a basis for defining a geometric path that the vehicle will follow. Viewing vehicle control as a simple geometry problem will not, however, lead to acceptable control of the vehicle.